Multifunction Elastomeric Plunger Seal Ring for Pump Packing
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Solution Overview
Problem
High-pressure plunger pumps in oil and gas fields face issues with leakage and premature failure due to excessive frictional heat and vibration, which limits operational duration and requires complex maintenance, as packing rings soften and extrude under pressure.
Innovation Solution
The introduction of multifunction elastomeric plunger seal rings with a totally-enclosed circumferential tubular cavity filled with a shear-thickening liquid that transmits hydraulic pressure and damps vibrations, reducing wear and heat generation by controlling radial expansion and heat transfer within the packing box.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If packing rings are made stiff to prevent leakage at high pressures, then sealing reliability improves, but frictional heat generation increases causing premature failure
Solution Approach 1:
The packing ring is constructed as a composite structure with a stiff outer layer (fabric-reinforced rubber) for sealing and a softer inner layer for compliance, combining the advantages of both material properties to reduce frictional heat while maintaining sealing reliability at high pressures
Solution Approach 2:
The packing ring material properties are optimized by adjusting the stiffness parameters of the layered construction, creating a balance between radial stiffness for sealing and longitudinal compliance to reduce frictional heating during operation
2Reliability
If longitudinal preload is increased to minimize seal leakage, then sealing performance improves, but plunger withdrawal complexity increases
Solution Approach 1:
The packing ring is designed with optimized dimensional parameters and material compliance that maintain effective sealing at reduced preload levels, allowing the plunger to be withdrawn without excessive force while still preventing leakage during operation
3Productivity
If pump run time is extended to improve productivity, then operational efficiency increases, but packing ring overheating and extrusion occur
Solution Approach 1:
A fluid-filled cavity is introduced as an intermediary heat transfer medium between the packing ring and the environment, efficiently carrying away frictional heat during pump operation and enabling extended run times without overheating
Solution Approach 2:
The packing ring incorporates an internal fluid-filled cavity that uses hydraulic principles to transfer heat away from the packing ring during pressure strokes, with the fluid absorbing and transporting thermal energy to prevent overheating during extended operation
4Reliability
If packing rings are made to fit tightly around plunger, then sealing effectiveness improves, but maintenance complexity increases
Solution Approach 1:
The packing ring is designed with optimized dimensional parameters including a slightly enlarged end face dimension that facilitates installation and removal while maintaining tight sealing contact with the plunger during operation, balancing sealing effectiveness with ease of maintenance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution extends plunger packing service life by reducing wear and heat-related failures, allowing for longer operational periods while minimizing maintenance complexity through controlled vibration damping and heat dissipation.
Implementation Method 1
The cavity is filled with a shear-thickening liquid (i.e., a dilatant liquid) which transmits hydraulic pressure throughout the tubular cavity
Implementation Method 2
damps pump vibration transmitted from the pump housing via the packing box
Implementation Method 3
increases coupling of packing box vibration to controlled hysteresis loss (i.e., heat loss) within the shear-thickening liquid
Implementation Method 4
facilitating heat transfer from plunger to packing box via the dilatant liquid
Implementation Method 5
Inward ring expansion tends to close the extrusion gap, thus reducing packing ring wear
Data Source
AI summary
One or more multifunction elastomeric plunger seal rings augment a plunger packing assembly within a plunger pump packing box. Each such ring comprises a totally-enclosed circumferential tubular cavity. The cavity is filled with a dilatant liquid which transmits hydraulic pressure throughout the tubular cavity and simultaneously damps pump vibration transmitted via the packing box. Pump pressure strokes increase tubular cavity hydraulic pressure, resulting in radial ring expansion forces both inwardly toward a plunger and outwardly toward its packing box. Inward ring expansion tends to close the extrusion gap, while outward expansion force improves heat transfer from plunger to packing box. Outward expansion force also increases coupling of packing box vibration to hysteresis loss in the dilatant liquid. During reductions in both pumped fluid pressure and associated pump vibration between pressure strokes, sealing and vibration damping functions of the rings are attenuated, reducing heat generation and frictional ring wear.